Pro-Arte, the world's most popular classical strings, are D'Addario's premium classical guitar string sets. All Pro-Arte treble strings are sorted by a sophisticated computer-controlled laser machine that performs diameter and tension measurements, ensuring true-sounding, precise trebles in every set. Pro-Arte basses are wound using silver-plated copper on a multi-filament nylon core for a consistent and warm, yet projecting tone. D'Addario offers a full range of classical guitar singles for all your replacement or customization needs. This is the perfect replacement string for the D'Addario EJ47 Pro-Arte 80/20 normal tension fourth string. Normal tension makes it ideal as a replacement string or for creating customized sets. Made in the U.S.A. for the highest quality and performance. String gauge: .033.